Saturday, October 18, 2014

Do you believe that drinking carbonated beverages containing sugar will cause your telomeres to shorten and hasten your death?

It's very difficult to teach students to be skeptical of the scientific literature and how it's reported. I read this press release from the University of California, San Francisco (San Francisco, USA) and dismissed it as ridiculous but I can't really tell you why. It's from one of the top research universities in the world.

What do you think? Do you believe this study? If not, why not? How do you explain why you are skeptical about this research but not about other research?

Sugar-sweetened soda consumption might promote disease independently from its role in obesity, according to UC San Francisco researchers who found in a new study that drinking sugary drinks was associated with cell aging.

The study revealed that telomeres — the protective units of DNA that cap the ends of chromosomes in cells — were shorter in the white blood cells of survey participants who reported drinking more soda. The findings were reported online October 16, 2014 in the American Journal of Public Health.

The length of telomeres within white blood cells — where it can most easily be measured — has previously been associated with human lifespan. Short telomeres also have been associated with the development of chronic diseases of aging, including heart disease, diabetes, and some types of cancer.

"Regular consumption of sugar-sweetened sodas might influence disease development, not only by straining the body's metabolic control of sugars, but also through accelerated cellular aging of tissues," said Elissa Epel, PhD, professor of psychiatry at UCSF and senior author of the study.

"This is the first demonstration that soda is associated with telomere shortness," Epel said. "This finding held regardless of age, race, income and education level. Telomere shortening starts long before disease onset. Further, although we only studied adults here, it is possible that soda consumption is associated with telomere shortening in children, as well."

The authors cautioned that they only compared telomere length and sugar-sweetened soda consumption for each participant at a single time point, and that an association does not demonstrate causation. Epel is co-leading a new study in which participants will be tracked for weeks in real time to look for effects of sugar-sweetened soda consumption on aspects of cellular aging. Telomere shortening has previously been associated with oxidative damage to tissue, to inflammation, and to insulin resistance.

Based on the way telomere length shortens on average with chronological age, the UCSF researchers calculated that daily consumption of a 20-ounce soda was associated with 4.6 years of additional biological aging. This effect on telomere length is comparable to the effect of smoking, or to the effect of regular exercise in the opposite, anti-aging direction, according to UCSF postdoctoral fellow Cindy Leung, ScD, from the UCSF Center for Health and Community and the lead author of the newly published study.

The average sugar-sweetened soda consumption for all survey participants was 12 ounces. About 21 percent in this nationally representative sample reported drinking at least 20 ounces of sugar-sweetened soda a day.

"It is critical to understand both dietary factors that may shorten telomeres, as well as dietary factors that may lengthen telomeres," Leung said. "Here it appeared that the only beverage consumption that had a measurable negative association with telomere length was consumption of sugared soda."

The finding adds a new consideration to the list of links that has tied sugary beverages to obesity, metabolic syndrome, type 2 diabetes, and cardiovascular disease, and that has driven legislators and activists in several U.S. jurisdictions to champion ballet initiatives that would tax sugar-sweetened beverage purchases with the goal of discouraging consumption and improving public health.

The UCSF researchers measured telomeres after obtaining stored DNA from 5,309 participants, ages 20 to 65, with no history of diabetes or cardiovascular disease, who had participated in the nation's largest ongoing health survey, called the National Health and Nutrition Examination Survey, during the years 1999 through 2002. They found that the amount of sugar-sweetened soda a person consumed was associated with telomere length, as measured in the laboratory of Elizabeth Blackburn, PhD, professor of biochemistry at UCSF and a winner of the 2009 Nobel Prize in Physiology or Medicine for her telomere-related discoveries.

###

Additional study authors include, from UCSF, Nancy E. Adler, PhD, professor of psychiatry and director of the Center for Health and Community, and Jue Lin, PhD, an associate researcher with Blackburn's lab; from UC Berkeley, Barbara A. Laraia, PhD, director of public health nutrition; from the University of Michigan, Belinda Needham, PhD, assistant professor of epidemiology; and from Stanford University, David H. Rehkopf, ScD, assistant professor of medicine.

14 comments
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OK, layman taking a stab at it here:Professor of psychiatry? o-0Why only soda and not other sources of sugar? Or is soda such a major dietary sugar source in North America, that we can use it as a good proxy for total intake?Also, what do "ballet initiatives" have to do with this? ;-) (I mean, it's good exercise and all....)

The main reason I feel skeptical towards it is that I feel skeptical towards all dietary research. A great deal of it is correlational crap, often with statistics that do not adequately take into account multiple-hypothesis testing in their experiments. This paper might not fit that trend, I haven't read it, but so much of this kind of research is poor that it's a useful prejudice. Also, a lot of dietary research seems driven by a latent Puritanism. It might turn out to be correct, but there is a reaching element there: death needs a scapegoat that's you're personal fault and/or a target for regulators.

Like Steve, I wonder why soda and not sugar in general? Or calories in general? And of course, what reason do they have to think that the direction of causality goes from more soda consumption to telomere length and not from telomere length to increased soda consumption? And how strong is this correlation anyway?

For all that it could be true, but for the most part I dismiss dietary research out of hand unless something tips me off that the authors have done a better job than most examples of the type.

"Better choice of diet and activities has great potential to reduce the rate of telomere shortening or at least prevent excessive telomere attrition ..."From:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3370421/

1. I take "carbonated beverages containing sugar" as a surrogate for eating lots of Jellied Donuts.2. No doubt the analysis could be flawed, but I'm sure there are scientists (from the DI) funded by Pepsi rechecking the sources and math as I write.3. If the results are accurate no doubt there are multiple steps from sugar intake to telomere shortening.

Such things aside I see no reason to doubt the results.

On the other hand, experience has taught me that folks who eat a lot of Jelly Donuts are certain to see many many problems with this work.

I think it is important for scientists to explain to students and the public that a genuine scientific explanation requires a mechanism -- it is not clear what possible mechanism there would be for soda causing telomeres to shorten.

Otherwise it is like the old joke about ice cream causing street crime on the basis of the correlation between ice cream sales and street crime (both high in summer and low in winter).

Larry is a biochemist, so I'm going to have him the privilege to dismiss the following claims:

"HFCS (High Fructose Corn Syrup)and cane sugar are NOT biochemically identical or processed the same way by the body. High fructose corn syrup is an industrial food product and far from “natural” or a naturally occurring substance. It is extracted from corn stalks through a process so secret that Archer Daniels Midland and Carghill would not allow the investigative journalist Michael Pollan to observe it for his book The Omnivore’s Dilemma. The sugars are extracted through a chemical enzymatic process resulting in a chemically and biologically novel compound called HFCS. Some basic biochemistry will help you understand this. Regular cane sugar (sucrose) is made of two-sugar molecules bound tightly together– glucose and fructose in equal amounts.The enzymes in your digestive tract must break down the sucrose into glucose and fructose, which are then absorbed into the body. HFCS also consists of glucose and fructose, not in a 50-50 ratio, but a 55-45 fructose to glucose ratio in an unbound form. Fructose is sweeter than glucose. And HFCS is cheaper than sugar because of the government farm bill corn subsidies. Products with HFCS are sweeter and cheaper than products made with cane sugar. This allowed for the average soda size to balloon from 8 ounces to 20 ounces with little financial costs to manufacturers but great human costs of increased obesity, diabetes, and chronic disease.Now back to biochemistry. Since there is there is no chemical bond between them, no digestion is required so they are more rapidly absorbed into your blood stream. Fructose goes right to the liver and triggers lipogenesis (the production of fats like triglycerides and cholesterol) this is why it is the major cause of liver damage in this country and causes a condition called “fatty liver” which affects 70 million people. The rapidly absorbed glucose triggers big spikes in insulin–our body’s major fat storage hormone. Both these features of HFCS lead to increased metabolic disturbances that drive increases in appetite, weight gain, diabetes, heart disease, cancer, dementia, and more.

But there was one more thing I learned during lunch with Dr. Bruce Ames. Research done by his group at the Children’s Hospital Oakland Research Institute found that free fructose from HFCS requires more energy to be absorbed by the gut and soaks up two phosphorous molecules from ATP (our body’s energy source).

This depletes the energy fuel source, or ATP, in our gut required to maintain the integrity of our intestinal lining. Little “tight junctions” cement each intestinal cell together preventing food and bacteria from “leaking” across the intestinal membrane and triggering an immune reaction and body wide inflammation.

High doses of free fructose have been proven to literally punch holes in the intestinal lining allowing nasty byproducts of toxic gut bacteria and partially digested food proteins to enter your blood stream and trigger the inflammation that we know is at the root of obesity, diabetes, cancer, heart disease, dementia, and accelerated aging. Naturally occurring fructose in fruit is part of a complex of nutrients and fiber that doesn’t exhibit the same biological effects as the free high fructose doses found in “corn sugar”.

The takeaway: Cane sugar and the industrially produced, euphemistically named “corn sugar” are not biochemically or physiologically the same."

"High doses of free fructose have been proven to literally punch holes in the intestinal lining." 1) What is defined as a "high dose." Is a 55:45 ratio -- compared to 50:50 ratio -- a "high dose"? 2) Intestinal linings of humans, or much smaller mammals? 3) Is Mark Hyman trying to argue that soda is really "punching holes" in people? What evidence is there of this. 4) Is the title of his article, "5 Reasons High Fructose Corn Syrup Will Kill You" sound reasonable, measured, or scientific? Best

Other points: anyone who can write “soaks up two phosphorous molecules from ATP (our body’s energy source)” clearly doesn’t know much biochemistry. You can’t say “soaks up” in a serious context. By “two phosphorous molecules” he means two phosphate ions, and not that they are derivatives of phosphoric acid, not of phosphorous acid. Finally, ATP is not “our body’s energy source” except in a very loose sense; it is the energy currency of the cell. The energy source is mainly sugar and oxygen.

Then we have “euphemistically named ‘corn sugar’”: that’s advertiser-speak, not science. There is nothing euphemistic about it, as it is sugar and it comes from corn syrup, so it’s just a descriptive term.

I used to know Bruce Ames when he was a newly appointed Full Professor at Berkeley and I was a post-doc. I heard him give a plenary lecture at a FASEB meeting in, if memory serves, 1977 in Chicago. In it he said (according to my memory) that within 25 years we would be seeing a huge increase in the incidence of cancer. 25 years later I remembered this, but I didn’t seem to be seeing the expected huge increase in the incidencd of cancer, so I went back to the printed record to see exactly what he had said. To my disappointment I could find none of that in his published lecture. This could of course just mean that I’d remembered it wrongly, but as I was quite impressed by the prediction at the time I find it hard to believe that I just imagined it. Anyway, this experience makes me more sceptical than I already was about reports of what people say orally (especially “during lunch”): people say all sorts of things at lunch that they might not want to commit to the printed record.

Oh dear, it still isn't right. Please treat the two comments above as a single one:

This computer doesn’t like the “Reply” button, so I’m doing this as a new comment, but it’s a reply to the stuff about corn syrup.

First of all I agree with what Keith and Cesar have written, so I won’t repeat it.

Other points: anyone who can write “soaks up two phosphorous molecules from ATP (our body’s energy source)” clearly doesn’t know much biochemistry. You can’t say “soaks up” in a serious context. By “two phosphorous molecules” he means two phosphate ions, and they are derivatives of phosphoric acid (phosphates), not of phosphorous acid (phosphites). Finally, ATP is not “our body’s energy source” except in a very loose sense; it is the energy currency of the cell. The energy source is mainly sugar and oxygen.

Then we have “euphemistically named ‘corn sugar’”: that’s advertiser-speak, not science. There is nothing euphemistic about it, as it is sugar and it comes from corn syrup, so it’s just a descriptive term.

I used to know Bruce Ames when he was a newly appointed Full Professor at Berkeley and I was a post-doc. I heard him give a plenary lecture at a FASEB meeting in, if memory serves, 1977 in Chicago. In it he said (according to my memory) that within 25 years we would be seeing a huge increase in the incidence of cancer. 25 years later I remembered this, but I didn’t seem to be seeing the expected huge increase in the incidencd of cancer, so I went back to the printed record to see exactly what he had said. To my disappointment I could find none of that in his published lecture. This could of course just mean that I’d remembered it wrongly, but as I was quite impressed by the prediction at the time I find it hard to believe that I just imagined it. Anyway, this experience makes me more sceptical than I already was about reports of what people say orally (especially “during lunch”): people say all sorts of things at lunch that they might not want to commit to the printed record.

Laurence A. Moran

Larry Moran is a Professor in the Department of Biochemistry at the University of Toronto. You can contact him by looking up his email address on the University of Toronto website.

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Quotations

The old argument of design in nature, as given by Paley, which formerly seemed to me to be so conclusive, fails, now that the law of natural selection has been discovered. We can no longer argue that, for instance, the beautiful hinge of a bivalve shell must have been made by an intelligent being, like the hinge of a door by man. There seems to be no more design in the variability of organic beings and in the action of natural selection, than in the course which the wind blows.Charles Darwin (c1880)Although I am fully convinced of the truth of the views given in this volume, I by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine. It is so easy to hide our ignorance under such expressions as "plan of creation," "unity of design," etc., and to think that we give an explanation when we only restate a fact. Any one whose disposition leads him to attach more weight to unexplained difficulties than to the explanation of a certain number of facts will certainly reject the theory.

Charles Darwin (1859)Science reveals where religion conceals. Where religion purports to explain, it actually resorts to tautology. To assert that "God did it" is no more than an admission of ignorance dressed deceitfully as an explanation...

Quotations

The world is not inhabited exclusively by fools, and when a subject arouses intense interest, as this one has, something other than semantics is usually at stake.
Stephen Jay Gould (1982)
I have championed contingency, and will continue to do so, because its large realm and legitimate claims have been so poorly attended by evolutionary scientists who cannot discern the beat of this different drummer while their brains and ears remain tuned to only the sounds of general theory.
Stephen Jay Gould (2002) p.1339
The essence of Darwinism lies in its claim that natural selection creates the fit. Variation is ubiquitous and random in direction. It supplies raw material only. Natural selection directs the course of evolutionary change.
Stephen Jay Gould (1977)
Rudyard Kipling asked how the leopard got its spots, the rhino its wrinkled skin. He called his answers "just-so stories." When evolutionists try to explain form and behavior, they also tell just-so stories—and the agent is natural selection. Virtuosity in invention replaces testability as the criterion for acceptance.
Stephen Jay Gould (1980)
Since 'change of gene frequencies in populations' is the 'official' definition of evolution, randomness has transgressed Darwin's border and asserted itself as an agent of evolutionary change.
Stephen Jay Gould (1983) p.335
The first commandment for all versions of NOMA might be summarized by stating: "Thou shalt not mix the magisteria by claiming that God directly ordains important events in the history of nature by special interference knowable only through revelation and not accessible to science." In common parlance, we refer to such special interference as "miracle"—operationally defined as a unique and temporary suspension of natural law to reorder the facts of nature by divine fiat.
Stephen Jay Gould (1999) p.84

Quotations

My own view is that conclusions about the evolution of human behavior should be based on research at least as rigorous as that used in studying nonhuman animals. And if you read the animal behavior journals, you'll see that this requirement sets the bar pretty high, so that many assertions about evolutionary psychology sink without a trace.

Jerry Coyne
Why Evolution Is TrueI once made the remark that two things disappeared in 1990: one was communism, the other was biochemistry and that only one of them should be allowed to come back.

Sydney Brenner
TIBS Dec. 2000
It is naïve to think that if a species' environment changes the species must adapt or else become extinct.... Just as a changed environment need not set in motion selection for new adaptations, new adaptations may evolve in an unchanging environment if new mutations arise that are superior to any pre-existing variations

Douglas Futuyma
One of the most frightening things in the Western world, and in this country in particular, is the number of people who believe in things that are scientifically false. If someone tells me that the earth is less than 10,000 years old, in my opinion he should see a psychiatrist.

Francis Crick
There will be no difficulty in computers being adapted to biology. There will be luddites. But they will be buried.

Sydney Brenner
An atheist before Darwin could have said, following Hume: 'I have no explanation for complex biological design. All I know is that God isn't a good explanation, so we must wait and hope that somebody comes up with a better one.' I can't help feeling that such a position, though logically sound, would have left one feeling pretty unsatisfied, and that although atheism might have been logically tenable before Darwin, Darwin made it possible to be an intellectually fulfilled atheist

Richard Dawkins
Another curious aspect of the theory of evolution is that everybody thinks he understand it. I mean philosophers, social scientists, and so on. While in fact very few people understand it, actually as it stands, even as it stood when Darwin expressed it, and even less as we now may be able to understand it in biology.

Jacques Monod
The false view of evolution as a process of global optimizing has been applied literally by engineers who, taken in by a mistaken metaphor, have attempted to find globally optimal solutions to design problems by writing programs that model evolution by natural selection.